SPECIAL DEFECTS OF THE MOLAR TEETH 327 



tained. Lancing the tumefied gums is sometimes resorted to with good 

 results. 



Numerical Excess and Deficiency of Development of Teeth. 



— Many instances occur in which the teeth are too numerous. When this 

 is so they are usually crowded together or appear out of their proper place. 



This irregularity of numbers may occur in the incisor teeth or the 

 molars, or both. We have known as many as ten of the former to be 

 present in the upper row instead of six, and we have seen as few as two. 

 Seven molar teeth instead of six on one side of the jaw is not of rare 

 occurrence (fig. 120), and we are aware of an instance where only one 

 molar tooth appeared in each jaw. When numerical excess leads to over- 

 crowding, a good deal of pain is the result; and much inconvenience 

 invariably occurs where the supernumerary teeth spring up, as they some- 

 times do, in the middle of the palate, or immediately within or without 

 the naturally placed row. In the former position they interfere with the 

 tongue, and in the latter with the cheeks, and in both they render masti- 

 cation difficult, and in some cases almost impossible. 



Where the number of teeth is deficient, grazing and mastication are 

 rendered troublesome in proportion to the extent of the loss. 



SPECIAL DEFECTS OF THE MOLAR TEETH 



Disparity of Length. — In this connection the most common defect 

 is that which results when the first and last molar teeth in the upper and 

 lower row do not exactly 

 cover each other. The 

 upper row may extend L, 



a little farther back than jf^^^^^T--^ - IjLl J't * 

 the lower one, when a WL ' J^^S^e^^^^^^X^^ 

 portion of the last tooth \jjj 

 of the former, and a por- 

 tion of the first tooth 

 of the latter, will lie out 

 of the line of wear (fig. 

 121), with the result 

 that the unused parts of 

 the teeth will grow of inordinate length, and sooner or later give rise to 

 difficulty of mastication, and maybe to injury of the gum, or even the 

 jaw-bone. To remedy this defect the projecting portions of the teeth 

 must either be removed with the rasp, or chiselled off with one or other 

 of the various chisels devised for the purpose. 



B 



